Die casting apparatus



June 10, 1941. c, VON YNN 2,244,816

DIE CASTING APPARATUS Filed Sept. 27. 19:59

Jig. 1.

INVENTOR Charles EVon Lynn w/atm ATTORNEY Patented June 10, 1941 DIECASTING APPARATUS Charles F. Von Lynn, Cranford, N. 1., assignor toAlumin um Company of America, Pittsburgh,

Pa., a corporation of Pennsylvania Application September 27, 1939,Serial No. 296,782

1 Claim. (CI. 22-68) This invention relates to die casting machines ofthe type employing a plunger to force into th mold cavitythe material tobe cast.

Die casting machines have heretofore been used in which molten materialto be cast is first introduced into a horizontally disposed well orreceptacle, and is then forced from the receptacle by means of a plungerreciprocable therein into a mold cavity formed by a stationary die and amovable die, which dies are replaceable in order to permit the making ofa variety of objects in the machine. In suchmachines, the stationary dieis provided with a horizontal transverse sprue hole which forms acontinuation of the bore of the receptacle mentioned, and together withthat bore forms the chamber into which the molten material to be cast isplaced preparatory to forcing it into the mold cavity. The injectingstroke carries the plunger into the sprue hole and almost to the dieparting line in order that as much as possible of the material beingcast may be forced into the mold cavity.

However, certain difficulties have been encountered with such machines.Since the injection stroke of the plunger carries it into the spruehole, and the sprue hole comprises part of the chamber from which themolten material is injected into the mold cavity, it is necessary thatthe sprue hole align accurately with the bore operation likewise varies.As a result, it is necessary to use receptacles and plungers of variouslengths if the stroke of the plunger is to remain constant.

A further difilculty is encountered when such machines are used forcasting the higher melting point metals, such as aluminum or brass,chiefly because of rapid deterioration of'the chamber from which themolten metal is forced by the plunger. To check deterioration of thereceptacle which forms part of that chamber, it has been proposed tocool it artificially by means of a suits able cooling chamber, but toprovide the sprue hole with a cooling chamber and the necessaryaccompanying mechanism complicates the die construction and assembly,and also results in detrimental fatigue stresses in the die.

It is an object of this invention to provide die casting apparatusof'the type described, in which a mold cavity is formed by a fixed dieand a movable die, and in which a plunger is reciprocable in a chamberformed by the bore of a receptacle and by a transverse sprue hole in thefixed die, but in which a plug fixedly attached to the movable dieprevents molten metal in the receptacle from fiowing into the moldcavity until pressure is applied to the metal by the plunger.

It is a further object of this invention to provide die castingapparatus in which a plunger is reciprocable in the bore of ahorizontally disposed receptacle and in a sprue hole which forms acontinuation of that receptacle bore, and in which a plug fixedlyattached to the movable die prevents molten metal in the receptacle fromfiowing into the mold cavity until pressure is applied to the metal bythe plunger, but cooperates with the wall of the sprue hole when thedies are in a closed position to provide a passage through whichthe'molten metal is forced into the mold cavity when pressure is appliedthereto.

It is a further object of this invention to provide die castingapparatus for the casting of high mleting point metals in which themetal is forced into the mold cavity by a plunger which isreciprocable'in a horizontally disposed receptacle and in asprue hole ina die, but in which the chamber in which the metal to be cast is placedlies within the receptacle mentioned and is artificially cooled alongsubstantially its entire length.

Referring to the drawing,

Fig. 1 is a vertical sectional view of a portion -of a die castingmachine embodying my invento the. fixed die i and'is provided with apouring hole 5 therein through which molten materialto be cast can bepoured into the bore 6 of the receptacle from a hand ladle or the like.The fixed die i is provided with a transverse sprue hole I which" formsa continuation of the receptacle bore 6 and communicates with the moldcavity 3 through the gate "I. Iiie sprue hole I is preferably slightlylarger in diameter] at its inlet end than the end of the sprue hole.Sumcient metal is poured into the receptacle I initially that when thecasting has been formed a small amount of the metal will remain in thereceptacle between the end of the from the mouth of the sprue holetoward the gate 8 and serves to conduct material being cast from thereceptacle 4 into the mold cavity 3 when pressure is applied thereto ashereinafter described. It is preferable that, except for the groove ill,the plug 9 fit closely in the sprue hole along its entire length'whlchprojects from the face of the movable die, though it is also possiblefor the plug to fit closely in the sprue hole only at the latters mouth.The plug 9 closes the mouth of the sprue hole 1 except for that portionthereof which iorms the entrance to the passage mentioned which isdefined by the wall of the groove l0 and the wall of the sprue hole, andsince the outlet of the groove I0 is above the level of the end of thereceptacle bore 8, moltenmaterial in the receptacle bore cannot flowinto the mold cavity without the application of pressure thereto. Thus,the plug 9 acts as a dam between the receptacle bore 6 and the moldcavity.

The plunger II is reciprocable in the bore 6 of the receptacle 4 for thepurpose of injecting into the mold cavity through the groove ill thematerial to be cast. The plunger II is preferably actuated by suitablehydraulic mechanism, and has a stroke sufllciently long to carry it intothe sprue hole I when the plug 9 is withdrawn from the sprue hole.During the injecting stroke of the plunger, the plug 9 occupies thesprue hole; and

' the materialto be cast is confined in the receptacle I between the endof the plunger Ii and the face of the plug until it is forced out of thereceptacle and into the mold cavity by the plunger. The receptacle 4 hasdouble walls which provide a cooling chamber l2 around the receptacle,extending'substantially the full length of that receptacle, so that acooling medium, such as water or air, can be circulated therein to coolthat element and molten material therein, the inlet pipe I3 serving tointroduce the cooling medium into the chamber l2, and the outlet pipe Hserving to carry away the coolant.

The apparatus described above operates as follows:

The movable die 2 is advanced to a closed position with the fixed die I,as shown in Fig.1,

' to form the mold cavity 3. During the closing of the dies, the plug 9advances into the sprue hole I until it closes the mouth of the spruehole except for the entrance to the passage formed by the groove l0 andthe wall of the sprue hole. With the plunger in a fully retractedposition, metal in a suitable condition for casting is poured into thereceptacle 4 through the pouring hole 5, after which plunger II isadvanced rapidly to force the metal into the mold cavity 3 through thepassage formed by the groove l0 and the wall plunger H and the face ofthe plug I. Meanwhile, cooling fiuid is circulated in the chamber l2through the pipes I l and I4. when the casting has solidified and themovable die is withdrawn to open the mold cavity, the movable diecarries with it the plug I, whereupon the plunger ll advances into thesprue hole I and ejects from the bore of the receptacle 4 and from thesprue hole any solidified metal therein.

With apparatus of the type described above, it is unnecessary that thesprue hole I align accurately with the bore of the receptacle 4,although it is essential that the sprue hole and receptacle bore align'suillciently to permit the plunger to advance into the sprue hole whenthe plug 9 is withdrawn. Consequently, it is possible for the sprue holeto taper outwardly from the receptacle, as shown in Fig. 1, and thatform of sprue hole is preferred since it facilitates removal of anysolidified metal remaining therein after the casting has solidified.

Various modifications can be made in the apparatus described abovewithout departing from the spirit of my invention or from the followingclaim. For example, although it is preferable that the outlet of thegroove ll be above the upper level ofthe receptacle bore i in order toprevent the metal in the receptacle from flowing .into the mold cavitywithout the application of I cavity.

I claim:

In a pressure casting machine including a fixed die and a movable diecooperating to form a mold cavity, a receptacle adjacent the fixed diefor supplying material to be cast, said receptacle having asubstantially horizontally disposed bore,

and said fixed die having a sprue hole therein forming a continuation ofsaid receptacle bore, a plunger reciprocable in said receptacle bore andin said sprue hole, and a plug fixedly attached to said movable die;when said dies are closed said plug extending into said sprue hole andterminating in a plane at the juncture of the sprue hole and receptaclebore, said plug and the wall of said sprue hole cooperating to form apassage therebetween communicating with said receptacle bore and saidmold cavity, the bottom of the entrance of said passage being above thelevel of molten metal within said receptacle when said plunger is in itsretracted position, and the mouth of said receptacle being closed bysaid plug except at the entrance of said passage, whereby said plugprevents molten metal within said receptacle bore from flowing into saidmold cavity prior to the application of pressure to the molten metal bysaid plunger.

- CHARLES F. VON LYNN.

